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LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 32
An Overview of Animal Diversity
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Seatwork 2
• Why is it important to study zoology?
(5 sentences) (10 points)
Overview: Welcome to Your Kingdom
• The animal kingdom extends far beyond humans
and other animals we may encounter
• Scientists have identified 1.3 million living species
of animals
© 2011 Pearson Education, Inc.
Figure 32.1
Concept 32.1: Animal are multicellular,
heterotrophic eukaryotes with tissues that
develop from embryonic layers
• There are exceptions to nearly every criterion for
distinguishing animals from other life-forms
• Several characteristics, taken together, sufficiently
define the group
© 2011 Pearson Education, Inc.
Nutritional Mode
• Animals are heterotrophs that ingest their food
© 2011 Pearson Education, Inc.
Cell Structure and Specialization
• Animals are multicellular eukaryotes
• Their cells lack cell walls
• Their bodies are held together by structural
proteins such as collagen
• Nervous tissue and muscle tissue are unique,
defining characteristics of animals
• Tissues are groups of cells that have a common
structure, function, or both
© 2011 Pearson Education, Inc.
Reproduction and Development
• Most animals reproduce sexually, with the diploid
stage usually dominating the life cycle
• After a sperm fertilizes an egg, the zygote
undergoes rapid cell division called cleavage
• Cleavage leads to formation of a multicellular,
hollow blastula
• The blastula undergoes gastrulation, forming a
gastrula with different layers of embryonic tissues
© 2011 Pearson Education, Inc.
Figure 32.2-3
Zygote
Cleavage
Blastocoel
Cleavage
Eight-cell
stage
Blastula
Cross section
of blastula
Gastrulation
Blastocoel
Endoderm
Ectoderm
Archenteron
Cross section
of gastrula
Blastopore
• Many animals have at least one larval stage
• A larva is sexually immature and morphologically
distinct from the adult; it eventually undergoes
metamorphosis
• A juvenile resembles an adult, but is not yet
sexually mature
© 2011 Pearson Education, Inc.
Figure 32.4
1.5 cm
(a) Mawsonites spriggi
0.4 cm
(b) Spriggina floundersi
Figure 32.5
Concept 32.3: Animals can be characterized
by “body plans”
• Zoologists sometimes categorize animals
according to a body plan, a set of morphological
and developmental traits
© 2011 Pearson Education, Inc.
Symmetry
• Animals can be categorized according to the
symmetry of their bodies, or lack of it
• Some animals have radial symmetry, with no
front and back, or left and right
© 2011 Pearson Education, Inc.
Figure 32.7
(a) Radial symmetry
(b) Bilateral symmetry
• Two-sided symmetry is called bilateral symmetry
• Bilaterally symmetrical animals have
–
–
–
–
A dorsal (top) side and a ventral (bottom) side
A right and left side
Anterior (head) and posterior (tail) ends
Cephalization, the development of a head
© 2011 Pearson Education, Inc.
Tissues
• Animal body plans also vary according to the
organization of the animal’s tissues
• Tissues are collections of specialized cells isolated
from other tissues by membranous layers
• During development, three germ layers give rise to
the tissues and organs of the animal embryo
© 2011 Pearson Education, Inc.
• Ectoderm is the germ layer covering the embryo’s
surface
• Endoderm is the innermost germ layer and lines
the developing digestive tube, called the
archenteron
© 2011 Pearson Education, Inc.
• Sponges and a few other groups lack true tissues
• Diploblastic animals have ectoderm and
endoderm
– These include cnidarians and comb jellies
• Triploblastic animals also have an intervening
mesoderm layer; these include all bilaterians
– These include flatworms, arthropods, vertebrates,
and others
© 2011 Pearson Education, Inc.
Figure 32.8
(a) Coelomate
Coelom
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
(b) Pseudocoelomate
Body covering
(from ectoderm)
Pseudocoelom
Digestive tract
(from endoderm)
Muscle layer
(from
mesoderm)
(c) Acoelomate
Body covering
(from ectoderm) Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
Figure 32.8a
(a) Coelomate
Coelom
Body covering
(from ectoderm)
Digestive tract
(from endoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
Figure 32.8b
(b) Pseudocoelomate
Body covering
(from ectoderm)
Pseudocoelom
Digestive tract
(from endoderm)
Muscle layer
(from
mesoderm)
Figure 32.8c
(c) Acoelomate
Body covering
(from ectoderm)
Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)